Imagine a process that can completely deburr a part in less time than it took to read this sentence — much less time. The thermal energy method removes burrs, flashing and trapped particles from practically any workpiece in just a few milliseconds. TEM works by placing a workpiece — or hundreds of workpieces — in a sealed, pressurized chamber, filling it with a mixture of methane gas and oxygen and then introducing a spark. The resultant explosion generates a 3,316° C (6,000° F) heat wave that instantaneously vaporizes burrs and loose matter but leaves the workpiece undamaged.

These hole saws are known as bimetal types because they're made from two types of steel. The body is made from spring steel and formed into a cup. Around the front edge of that cup is brazed a circular row of cutting teeth made from a narrow band of high-speed steel. The result is a light weight and durable accessory tough enough to make big holes in wood  or metal. Suppose you need to make a door knob hole in a wood door; turn to these. Use them again to make holes in steel, for a tool rack, say.

However, these traditional deburring methods are slow. Features that can’t be reached while in a machine — which is often much of a part — must be manually scraped, buffed and chamfered. If an operator isn’t paying attention, a machine tool might sit idly while he or she is busy deburring parts. And a bit too much pressure with a grinding wheel or blade could mean the inadvertent scrapping of a completed, possibly very expensive machined component.

Spade bits are made for quick-and-rough holes in construction lumber. They don’t leave a particularly clean exit hole, but in most cases that doesn’t matter. Of all the spade bits we’ve tried through the years, we keep coming back to Irwin Speedbor. They’re inexpensive, tough, and can be sharpened with a file. One set will last for years, maybe decades, depending on your use.

Using an automated deburring tool like the Cofa, tedious deburring of small parts by hand can be eliminated for maximum efficiency and burr-free parts. Image courtesy of Heule Tool

“They’re also scalable in the sense that we have customers with multimillion-dollar equipment installations to those with fewer than 20 employees who process lot sizes of 400 to 1,000 pieces per production run,” Boutantin said. “Between TEM, AFM, ECM and their variants, we have solutions for practically any deburring need.”

“There are still an awful lot of people out there doing it by hand,” Baumet said. “Sometimes it’s because that’s all they know, other times because they don’t want to spend the money on a dedicated deburring tool. Either way, there’s plenty of room for improvement.”

Here again, multiple grades, geometries, diameters and lengths are offered, and both companies provide application and programming advice to those getting started. While Dean and Baumet might not agree on which brand of deburring tools a shop should buy, they do agree that deburring is a machining process that bears lots of low-hanging fruit.

If your drill driver has a hammer setting, chuck in one of these bits and make a clean and fast hole in concrete, brick, concrete block, or mortar. You don’t need an extensive set of masonry bits; a basic carbide-tip kit like this one is a great choice. Its German-made quality should provide years of use, and its slim, vinyl wallet enables it to slip into a crevice in your tool box. Carry this and you’re prepared for tough, masonry drilling jobs without having to make a quick run to a hardware store or home center.

Also available are the Cofa “universal deburring tool” for elliptical or contoured surfaces, the Defa adjustable chamfering tool and the X versions of Snap and Cofa for deburring cross-holes and intersecting bores.

“AFM uses a puttylike abrasive media that is forced under pressure through or around a workpiece, removing burrs and smoothing surfaces as it passes,” Boutantin said, “while ECM employs a shaped cathode and electrolytic fluid to quickly erode even stubborn burrs.”

Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.

Dean said Handi-Burr typically is reserved for manual deburring operations in a drill press or power tool while Burr-Zit is suitable for CNC and manual equipment. He also said both tool types are only for deburring, in that they produce a rounded edge. If a qualified, dimensionally accurate chamfer is needed, it should be machined using an actual milling cutter.

Liquid used to improve workpiece machinability, enhance tool life, flush out chips and machining debris, and cool the workpiece and tool. Three basic types are: straight oils; soluble oils, which emulsify in water; and synthetic fluids, which are water-based chemical solutions having no oil. See coolant; semisynthetic cutting fluid; soluble-oil cutting fluid; synthetic cutting fluid.

“The ease of setup is largely due to our Fastsimu programming and simulation software,” he said. “It allows you to import the CAD model and generate the toolpaths, the inspection points, check for collisions — all offline. There’s no more standing on the shop floor with a teach controller nudging the head this way and that or trying to figure out how much wheel pressure to apply. And because there’s a toolchanger and the option for a tool magazine, you can easily switch to whatever deburring tool or abrasive wheel is most appropriate for the application. There are very few parts that the RFC can’t complete in a single deburring operation, with changeover often taking just a few minutes.”

David Suica offers a novel though unsurprising approach to deburring, one that often trumps in-machine and manual processes alike. The president of automation systems provider Fastems LLC, West Chester, Ohio, said the company’s self-contained robotized finishing cell comes equipped with an industrial robot and gripper system, an automatic toolchanger and a servo-powered rotary workholding table and can have electric or pneumatic spindles. The RFC is easy enough to set up that it’s suitable for low-volume, high-mix work.

Use: Wood | Type: Forstener | Number of bits: 8 | Size range: ¼ to 1⅜ inchesWhen you need a perfectly round hole in wood with a smoothly machined sidewall, then you want a Forstener bit. These are best used in a drill press, but the smaller-diameter bits can be used in a hand drill.

“You don’t want to pay CNC machinists to deburr holes,” said Samuel Dean, director of sales and marketing at Whitney Tool Co. Inc., Bedford, Indiana. “You want to pay them to program and set up and maintain machinery, which means that the deburring — or as much of it as possible — is done inside the machining center where consistency is assured and there’s no chance of missing a hole. This is why it’s so important to convert manual deburring operations into automated ones so that shops can more efficiently utilize their production floor staff.”

This self-contained robotized finishing cell boasts an industrial robot and gripper system and is suitable even for low-volume, high-mix work. Image courtesy of Fastems

Carriage or drum attached to a machining center that holds tools until needed; when a tool is needed, the toolchanger inserts the tool into the machine spindle. See automatic toolchanger.

Use: Wood and steel | Type: Extra-long twist drill | Number of bits: 5 | Size range: ¼ to ½ inchSuppose you need more reach when making a hole, such as when you’re working on an old house or restoring an old car. Or in a modern house, you need a super-long pilot hole for that massive screw you’ll use to hang a ceiling fan. Enter these 18-inch bits. Built from high-speed steel and with geometry to eject metal chips, they work on wood, too (though you will have to back them out repeatedly as you go deeper to eject the wood chips).

Worker health and safety are also a consideration. As machinists would attest, cuts, scrapes and repetitive stress injuries are common during manual deburring, never mind the potential inhalation of abrasive grit. Surely safer, more productive methods are available?

Operation in which electrical current flows between a workpiece and conductive tool through an electrolyte. Initiates a chemical reaction that dissolves metal from the workpiece at a controlled rate. Unlike with traditional cutting methods, workpiece hardness is not a factor, making ECM suitable for difficult-to-machine materials. Takes such forms as electrochemical grinding, electrochemical honing and electrochemical turning.

“Considering the difficulty that everyone faces in finding qualified people,” he said, “plus the call for unattended machining in an environment that’s increasingly demanding, the need for this level of automated deburring is clear.”

Use of rapidly spinning wires or fibers to effectively and economically remove burrs, scratches and similar mechanical imperfections from precision and highly stressed components. The greatest application is in the manufacture of gears and bearing races where the removal of sharp edges and stress risers by power methods has increased the speed of the operation.

“The wheels wear well, are coolant-proof, and most CNC machine tools these days have some level of cutting fluid filtration, lowering concerns over grit and contaminants getting into the way surfaces,” he said. “So with that in mind, it’s not a huge leap to mount a nonwoven wheel in a CNC machining center and use it for part deburring and finishing operations. Whether you’re using these products in an automated environment or a manual one, however, I strongly advise that shops review their abrasive wheel and disc selections every few years because we’re constantly improving both.”

Use: Thin-gauge steel, aluminum | Type: Impact-rated step drill | Number of bits: 3 | Size range: ⅛ to ⅞ inchThey call these step drills because of their shape. Each step increases the hole diameter. You just stop drilling when you reach the appropriate hole diameter at the step that produces it. Although these bits are designed for sheet metal, they will drill a clean fast hole in heavier-gauge materials like electrical boxes and even mild steel channel, and shapes like L, U, and T.

Kip Hanson is a contributing editor for Cutting Tool Engineering magazine. Contact him by phone at (520) 548-7328 or via e-mail at kip@kahmco.net.

Matt Baumet, technical sales engineer at Heule Tool Corp., Loveland, Ohio, suggested several similar alternatives. The company’s Snap front and back chamfering tools, for example, feature a replaceable, spring-loaded blade and are intended for use with CNC machine tools while providing more accurate chamfering than tools for only deburring.

If you’re getting interested in woodworking, this inexpensive brad point bit set is an easy choice. The sharp tip on these bits make it easy to start the bit exactly where you need it, and their geometry—somewhere between a twist drill and an auger bit—makes for good chip ejection.

Bruno Boutantin, global marketing director for Extrude Hone LLC, Irwin, Pennsylvania, said suitable TEM applications include die castings and machined parts of all shapes and sizes, but the approach is popular in the heavy equipment industry. This popularity is due to TEM’s fast cycle times, consistency and cost-effectiveness. The method is often ideal for deburring manifolds and other large, high-volume components.

Wheel formed from abrasive material mixed in a suitable matrix. Takes a variety of shapes but falls into two basic categories: one that cuts on its periphery, as in reciprocating grinding, and one that cuts on its side or face, as in tool and cutter grinding.

Runs endmills and arbor-mounted milling cutters. Features include a head with a spindle that drives the cutters; a column, knee and table that provide motion in the three Cartesian axes; and a base that supports the components and houses the cutting-fluid pump and reservoir. The work is mounted on the table and fed into the rotating cutter or endmill to accomplish the milling steps; vertical milling machines also feed endmills into the work by means of a spindle-mounted quill. Models range from small manual machines to big bed-type and duplex mills. All take one of three basic forms: vertical, horizontal or convertible horizontal/vertical. Vertical machines may be knee-type (the table is mounted on a knee that can be elevated) or bed-type (the table is securely supported and only moves horizontally). In general, horizontal machines are bigger and more powerful, while vertical machines are lighter but more versatile and easier to set up and operate.

CNC machine tool capable of drilling, reaming, tapping, milling and boring. Normally comes with an automatic toolchanger. See automatic toolchanger.

Mechanism typically included in a machining center that, on the appropriate command, removes one cutting tool from the spindle nose and replaces it with another. The changer restores the used tool to the magazine and selects and withdraws the next desired tool from the storage magazine. The changer is controlled by a set of prerecorded/predetermined instructions associated with the part(s) to be produced.

Image

Operation in which electrical current flows between a workpiece and conductive tool through an electrolyte. Initiates a chemical reaction that dissolves metal from the workpiece at a controlled rate. Unlike with traditional cutting methods, workpiece hardness is not a factor, making ECM suitable for difficult-to-machine materials. Takes such forms as electrochemical grinding, electrochemical honing and electrochemical turning.

Image

Rotary tool that removes hard or soft materials similar to a rotary file. A bur’s teeth, or flutes, have a negative rake.

Substance used for grinding, honing, lapping, superfinishing and polishing. Examples include garnet, emery, corundum, silicon carbide, cubic boron nitride and diamond in various grit sizes.

One step in this conversion process is the use of Burr-Zit and Handi-Burr deburring systems from Whitney Tool, he said. Often referred to as clothespin tools, Burr-Zit deburrs the front and back of hole diameters from 1.98 mm to 25.4 mm (0.078" to 1") in a single in-and-out pass. The Handi-Burr line of spring-loaded deburring tools extends that diameter range to 50.8 mm (2"). Multiple lengths, geometries and coatings are available, and the Burr-Zit series can be purchased in kit form to cover a range of hole sizes.

Okay, by now you might be saying to yourself, “All I want is a basic set of bits for wood and metal. Got any of those?” Yes. For less than $20 you get a high-quality hex shank bit with a highly wear-resistant titanium nitride coating. And if you up your game some day to include working with an impact driver, these bits will work with it.

Although relatively new, such systems are becoming popular, Suica said. As alluded to earlier, automated deburring raises fewer health and safety issues than manual deburring. Part quality is similarly improved, with no worries over an expensive machine tool sitting idly while the operator tends to a drill press or buffing wheel. And because the robot acts as a hardworking assistant to the CNC machine tool — or flexible manufacturing system — more machine uptime is possible.

Machine designed to rotate end-cutting tools. Can also be used for reaming, tapping, countersinking, counterboring, spotfacing and boring.

Finishing and deburring operation for holes, inaccessible areas or restricted passages. Done by clamping the workpiece in a fixture, then extruding semisolid abrasive media through the passage. Often, multiple parts are loaded into a single fixture and finished simultaneously.

Loosely, any milling tool. Horizontal cutters take the form of plain milling cutters, plain spiral-tooth cutters, helical cutters, side-milling cutters, staggered-tooth side-milling cutters, facemilling cutters, angular cutters, double-angle cutters, convex and concave form-milling cutters, straddle-sprocket cutters, spur-gear cutters, corner-rounding cutters and slitting saws. Vertical cutters use shank-mounted cutting tools, including endmills, T-slot cutters, Woodruff keyseat cutters and dovetail cutters; these may also be used on horizontal mills. See milling.

How To Select a SetThere’s no sense in getting bogged down in complexities of hole making–the fine points belong to industrial users. For the rest of us, all we really need to know are the basics. That’s why we separate out bits for making holes in wood, metal, masonry (concrete or stone), and tile/glass. Some of the drill bits do a pretty good job making holes in more than one material. Other than selecting a bit based on the material you’re drilling, keep in mind the quality of the hole you’re making. That sounds odd. A hole is a hole, right? Wrong, There’s a big difference between a perfectly round and smooth-walled hole for furniture making than a rough-and-ready hole made in framing lumber to fit a pipe or cable. So think about the material, the hole itself, and how you want to make it. Choose your set accordingly.

Suppose your drill doesn’t have a hammer function or you lack a dedicated masonry drill, what do you do then? Well, if your masonry hole drilling is confined to brick, concrete block, or mortar, you can use these inexpensive carbide-tip rotary drill bits for masonry. They won’t stand up to use in a hammer drill, but they work perfectly well, if slower, in a standard drill or cordless drill driver. Bonus: Their double-flute design allows better clearing of dust and chips compared to a single-twist type. This way you can use the drill’s high-speed setting to get through the job faster. Note that there are multiples of the smaller diameters, such as the 3⁄16-inch size, which are more frequently used with masonry screws.

“The Cofa and Cofa-X are specifically designed for irregular surfaces,” Baumet said. “Let’s say you’re deburring a hole drilled on an angled surface or a cross-hole in a piece of tubing. Here, the blade actually pivots in and out of the holder for continuous engagement. You get a nice, even chamfer all around the hole instead of the football shape you’d see using a standard chamfer tool.”

Robot designed for industrial use. Primarily used as a material-handling device but also used for changing tools, assembling parts, and manipulating special tools and measuring devices. Depending on design, an industrial robot can be programmed to perform a task by means of a controller, or it can be “walked” through the required movements by utilizing a digitizing system that translates movements into commands that the robot can be “taught.” See robot; teaching pendant.

It’s often said that you don’t need a drill bit; what you need is a hole. How you make that hole is up to you, but it’s a given that you want to make it as efficiently as possible. The drill bit, therefore, is built to match the diameter and length of the hole you want to make—as well as the material in which it works. And chances are good that you need more than one bit, you probably need at least a small set to make holes of various diameters.

Big HolesIf you need to make large-diameter holes—something between ¾ inch and 4 inches, let’s say. You don’t want a drill bit, you want a hole saw. Even though these aren’t drill bits, we’ve included a set of these at the bottom of this review. It’s reasonably priced and can serve both homeowners and professional users.

The T350 and T450 (pictured) thermal deburring machines offer a fast, cost-effective way to remove burrs and loose material. Image courtesy of Extrude Hone

Both processes are scalable, accommodating large parts, such as crankshafts, and relatively small parts, such as turbine blades and fuel nozzles.

Machining operation in which metal or other material is removed by applying power to a rotating cutter. In vertical milling, the cutting tool is mounted vertically on the spindle. In horizontal milling, the cutting tool is mounted horizontally, either directly on the spindle or on an arbor. Horizontal milling is further broken down into conventional milling, where the cutter rotates opposite the direction of feed, or “up” into the workpiece; and climb milling, where the cutter rotates in the direction of feed, or “down” into the workpiece. Milling operations include plane or surface milling, endmilling, facemilling, angle milling, form milling and profiling.

Any manufacturing process in which metal is processed or machined such that the workpiece is given a new shape. Broadly defined, the term includes processes such as design and layout, heat-treating, material handling and inspection.

Just as holemaking is common in metalworking, so is deburring the tops and bottoms of produced holes. Chamfering tools are effective, as are the familiar Rotoburr-style scraper blades. These tools also deburr machined edges fairly well and, given the right extension or blade geometry, can access hard-to-reach areas deep inside parts. Add a few Scotch-Brite pads, a drill press and a bench grinder to the mix, and there’s little that any skilled machine operator can’t deburr.

The only sure way to make consistent and clean holes in glass and ceramic tile is with a carbide bit designed for those materials. These simple and inexpensive little bits work great. The carbide tip is diamond ground to a sharp point that enables a fast and sure start, putting the hole right where you need it, instead of the bit skating off and leaving a nasty mark. The three flats ground onto the bit’s shank prevent it from slipping.

Use: Concrete, brick, mortar, concrete block | Type: Hammer-rated carbide-tip twist drill | Number of bits: 7 | Size range: 3⁄16 to ½ inch

These twist drill bits are built to withstand punishment. They’re machined out of high-speed steel and finished with a wear-resistant coating. Yet their tips can be resharpened. All that is good. What’s even better is that they’re made in America and yet are priced reasonably, especially when you account for the cost of the nice sheet steel bit index that they come in. We tried them, liked them, and thought enough of them to award them our coveted annual Tool Award.

It’s almost a sure bet that when running pipe and wire in an old house, you’re bound to hit embedded nails when boring the holes. That’s where these bits come in. They’re thicker than the typical spade bit to resist bending, and they have a bevel on their cutting surfaces suitable for both wood and metal.

That covers hole deburring, but what about smoothing the sharp, often ragged edges found on pockets, bosses, ribs and other machined features? Mike Shappell, senior application engineer at Norton | Saint-Gobain Abrasives, Worcester, Massachusetts, said programming the toolpaths needed for a chamfer mill or radius cutter isn’t terribly difficult, eliminating some if not all manual deburring. What’s more, some shops are morphing those toolpaths for use with one of the company’s nonwoven, unified or convolute abrasive wheels.

Automated manufacturing system designed to machine a variety of similar parts. System is designed to minimize production changeover time. Computers link machine tools with the workhandling system and peripherals. Also associated with machine tools grouped in cells for efficient production. See cell manufacturing.

The ability to deburr both sides of a hole (above) in a single operation is a huge timesaver. Image courtesy of Whitney Tool

Image

Machining operation in which material is removed from the workpiece by a powered abrasive wheel, stone, belt, paste, sheet, compound, slurry, etc. Takes various forms: surface grinding (creates flat and/or squared surfaces); cylindrical grinding (for external cylindrical and tapered shapes, fillets, undercuts, etc.); centerless grinding; chamfering; thread and form grinding; tool and cutter grinding; offhand grinding; lapping and polishing (grinding with extremely fine grits to create ultrasmooth surfaces); honing; and disc grinding.

Use: Concrete block, mortar, brick | Type: Rotary (non hammer) carbide-tip twist drill | Number of bits: 14 | Size range: ⅛ to ½ inch

If you’re gearing up for your first big wiring or pipe job, or if you’re a seasoned pro looking for faster and cleaner hole-making ability, then self-feed bits are the way to go. The lead screw pulls the bit through the lumber while an interior plane shaves the wood as the bit turns. The result is a fast hole and a clean one. For the sake of longevity, the plane blade is sharpenable and the kit includes two removable, replaceable feed screws, because you’re bound to hit fasteners and chew through knots.

“It depends on the hole size and material,” he said, “but you could expect to hold plus or minus a couple thousandths on a chamfer.”